An index published in 1982 by Christopher Newhall and Stephen Self, for rating the explosivity of volcanic eruptions.1 Acronym, VEI.
| Criteria1 | VEI | ||||||||
|---|---|---|---|---|---|---|---|---|---|
| 0 | 1 | 2 | 3 | 4 | 5 | 6 | 7 | 8 | |
| Description | non-explosive | small | moderate | moderate to large | large | very large | |||
| Volume of ejecta (cubic meters) |
<104 | 104– 106 |
106– 107 |
107– 108 |
108– 109 |
109– 1010 |
1010– 1011 |
1011– 1012 |
>1012 |
| Tsuya class2 | I | II-III | IV | V | VI | VII | VIII | IX | |
| Column height (kilometers)3 |
<0.1 | 0.1-1 | 1-5 | 3-15 | 10-25 | >25 | |||
| Qualitative description |
gentle, effusive | explosive | cataclysmic, paroxysmal, colossal | ||||||
| severe, violent, terrific | |||||||||
| Classifications | Strombolian | Plinian | |||||||
| Hawaiian | Vulcanian | Ultraplinian | |||||||
| Duration of continuous blast (hours) |
<1 | >12 | |||||||
| 1-6 | |||||||||
| 6-12 | |||||||||
| CAVW maximum explosivity4 | lava flows | explosion or nuée ardente | |||||||
| phreatic | |||||||||
| dome or mudflow | |||||||||
| Tropospheric injection | negligible | minor | moderate | substantial | |||||
| Stratospheric injection | none | none | none | possible | definite | significant | |||
After Newhall and Self.
1. Christopher G. Newhall and Stephen Self.
The volcanic explosivity index (VEI): An estimate of explosive magnitude for
historical volcanism.
Journal of Geophysical Research, volume 87 number C2, pages
1231-1238 (20 February 1982).
1. Criteria are listed in decreasing order of reliability.
2. Tsuya classification (based on volume of ejecta), assuming pyroclastic flows. The scale is defined in:
H. Tsuya.
Geological and petrological studies of volcano Fuji, 5.
Tokyo Daigaku Jishin Kenkyusho Iho, volume 33, pages 3-382 (1955).
3. For VEI's 0 – 2, measured from the crater rim; for VEI's 3 – 8, measured from sea level.
4. Most explosive activity indicated for the eruption in the Catalog of Active Volcanoes of the World.
| Volcano | Date of Eruption | VEI |
|---|---|---|
| Krakatau | 26 Aug 1883 | 6 |
| Mt. St. Helens | 18 May 1980 | 5 |
| Mt. St Helens | 1540 ± 70 | 5 |
| Tambora | 5 April 1815 | 7 |
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